Control mechanism



Feb. 23, 1954 E. F. RossMAN CONTROL MECHANISM 4 Sheets-Shget 1 FiledJan. 29. 1948 ATTIQNEYS Feb. 23, 1954 E. F. RossMAN 2,670,201 coNTRor.MECHANISM Filed Jan. 29. 1948 4 Sheets-Sheet 2 Feb. 23, 1954 E. F..Ros\sMAN CONTROL MECHANISM Filed Jan. 29. 1948 JNVENTOR.

sow/N F. @ass/wm BY WIJ/WQ@ /5 ATTO/2HE Ys Feb. 23, 1954 E. F. RossMANCONTROL MECHANISM 4 Sheets-Sheet 4 Filed Jan. 29, 1948 ng. zz.

INVENTOR. IOW/N F. @OSS/VAN BY am, ht

,5 ATa/P/YEYS 'Patented Feb. 23, 1954 2,670,201 CONTROL MECHANISM EdwinF. Rossman,

Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Application January 29, 1948, Serial N o. 5,1699 Claims. (Cl. 267-65) This invention relates to an improved actuatingmechanism for the vcontrol device of a pneumatic suspension system formotor vehicles.

The present invention is particularly adapted for use in connection witha vehicle suspension system in which air springs provide'the resilientmeans for supporting the body of the vehicle upon its running gear oraxles. The air spring may be in the form of an air cushion, a bellows ora piston and cylinder inflated or charged witha volume of iluid,preferably air, under sufficient pressure to support the body of thevehicle above the axle.

The total relative movement between the body and axle of a vehicle islimited by the construction of the suspension to meet certainspecifications of height, space, appearance and operation of thevehicle. Some vehicles, such as passenger busses and the like, areoperated under substantial load variations and if the air springs arepermanently inilated for the average load, with no compensating controlssuch as are provided by the present invention, the vehicle will ride toolow at full or excessive loads and too high at no load. Excessiveloading will cause bottoming, that is, the striking of the axles by thebody supporting frame and under no load the vehicle rides too high forsafe operation.

To get full beneilt from the use of comfortable riding air springs andavoid bottoming or unsafe high riding conditions,` it is necessary toadjust the air springs by inflation or deflation. For best results it isdesirable to so innate lor deflate the air springs automatically inresponse to changes in the average riding clearance between the vehiclebody carrying frame and the axles, thereby substantially maintain thesaid frame at its normal riding height regardless of load condition;

An object of the present invention is to provide an actuator for an airspring inflation or deflation control device operative only in responseto predetermnately slow relative movements between the sprung andunsprung masses resulting from an increase or decrease of loadv above orbe-i springs in accordance with increases or decreases the vehicle.

height if desirable Further objects and advantages of the presentapparent from the following description, reference being had to theaccolnpanying drawings wherein a preferred embodiment is clearly shown.

In the drawings:

Fig. 1 is a fragmentary side view of the vchassis of a vehicle equippedwith the presentinventlon.

Fig. 2 is a rear View of the chassis shown in Fig. 1.

Fig. 3 is a plan view of the chassis section shown in Fig. 1.

Fig. 4 is a sectional view taken substantially along the line 5-5 ofFig. 6, certain parts being shown in elevation and in the line of thesection for the sake of clarity.

Fig. 5 is a fragmentary sectional view taken from Fig. 5, and showingthe valve operating element in one of its valve actuating positions.

Fig. 6 is a plan view of the control device.

Fig. '7 illustrates the device in front elevation.

Fig. 8 is a view of one end of the device. V

Fig. 9 is an end view opposite to that` oi Fig. 8.

Fig. 10 is a sectional view taken substantially along the line lll- I0of Fig. '7.

Fig. 11 is a sectional view taken `substsmtially along the line H`I| ofFig. 8.

Fig. 12 is a piston in the of the device.

movement dampener mechanism Referring to the drawings the controldevice' and its actuator of the present invention is shown as a unitarystructure comprising a housing 20 in which an osclllatable lever 2lisjournalled. YThe housing 20 is adapted to be attached to one of thetwo relatively movable members, the sprungmass or body carrying frame22, while the lever 'Z is adapted to be attached by suitable linkagetothe other member, the unsprung mass or axle 23 of This is clearlyillustrated vin the Figs. 1, 2 and 3 which also show one method ofsupporting the frame 22 on the axle 23 by means of air springs 24illustrated in the form of ex pansible or contractible bellows.

For purposes of illustrating one form of in-y 22, the other end Vof eachbeam' to the one end plate of van 'air longitudinal sectional view oftheis shown having cross ricains secured toa bracketfianchored spring 24,its other end plate engaging and supporting the frame 22. Any suitablelinkage 21 secures the free end of the oscillatable lever 2| of thecontrol device 20 to the axle 23. Road wheels 28 are provided on theaxle 23.

Assuming that the Figs. l and 2 show the vehicle frame 22 at theselected normal riding height, then loading of the vehicle wouldcompress and deflect the bellows or air springs 24 by the lowering ofthe frame 22 due to the increased load. An extremely heavy load would socompress the air springs that possible striking of parts and damagewould result. To avoid this the air springs may be inflated by theintroduction of a fluid, preferably air, under pressure thereby liftingthe frame 22. If the ination is controlled in accordance with the loadadded to the frame 22, then the normal riding height of the frame 22,relatively to the axle, may be maintained under any load conditions.

If however, only inflation is controlled in accordance with the appliedload removal of the load would permit the air springs 24 to expand andupon complete removal of the load the frame 22 would be raisedsubstantially above the normal riding height and make operation of thevehicle, particularly at higher speed, extremely hazardous. On the otherhand, however, if as the frame is raised by the air springs, due to thedecrease in the load on the frame, the uid or air pressure in the airsprings is accordingly reduced, then said air springs are deflated inaccordance with the diminishing load and the frame is consequentlymaintained at the normal riding height.

As has been stated, the device of the present invention is designed andconstructed to control the inflation and deflation of air springs in'accordance with the relative positions of the sprung and unsprungmasses of a vehicle thereby sub stantially maintaining the sprung massat a predetermined mean riding height regardless of the load thereon.

The control mechanism of the present invention has been referred to as aunit and comprises two portions 35 and 30 secured together by bolts 31.The portion 35 of the device contains all the fluid or air passages andthe controlling valves. The portion 36 contains the control valveactuating mechanism and the dampening device for resisting the movementof said control valve mechanism under predetermined conditions. Bothportions 35 and 3B, bolted together, form what has been termed thehousing 20 which, as shown in Figs. l, 2 and 3 is attached to the sprungmass or frame 22 of the vehicle.

Portion 35 of the housing has a threaded inlet port 3B for receiving oneend of a conduit or pipe, the other end being connected to a reservoir,charged with air under pressure by a pump.

The housing portion contains suitable valving to be actuated, saidvalving having stems 61 and 8S extending from the housing portion 35 andbeing engageable by the actuator lever H6.

The housing portion 36 contains the mechanism for operating theinflation and vdeflation control valve stems 61 and 86. As shown inFigs. 4 and 10, portion 36 has a chamber |00, the one open side of whichis clamped against the housing portion 35 by the bolts 31. As has beenmentioned previously, the actuating pins 61 and 86 of the inflation 'anddeiiation control valve assemblies extend from said housing portion 35into the chamber |00. The inner wall opa posite the open side of portion36 has an opening |02 provided therein. A cylindrical passage |03, openat both ends, is provided in the portion 36 directly beneath the innerwall |0|. Each end of the cylinder |03 is closed by a sealed screw plug|04. A piston |05 forms a fluid displacement chamber at each end of thecylinder |03, the one chamber being designated by the numeral |06, theother by numeral |01.

Adjacent the cylinder |03, housing portion 30 has a fluid passage |08which connects the two fluid displacement chambers |06 and |||i1 therebyproviding for the transfer of fluid between said 'chambers as the piston|05 is reciprocated in the cylinder |03. Abore |09 from outside thehousing portion 36 communicates with the passage |08, forming an annularseat H0 at its point of communication with said passage. Bore |09 isinteriorly threaded to receive an adjustable metering pin the inner,tapered end of which being movable, by the turning of the pin intoselectable juxtaposition to the seat H0 to provide any desirablerestriction to the iiow of the incompressible fluid through passage |03in either direction.

As shown in Figs. 5 and l0, a shaft H5 is journalled in the housingportion 36, transversely thereof and substantially equidistant from bothactuating plungers Si' and 86 of the inflation and deation valves 05 and85 respectively. One end of shaft |5 extends through its bearing and anadjacent packing gland ll'a, to the outside of the housing, this end ofthe shaft having the operating arm 2| attached thereto. The free end ofthis arm is adapted to be attached to the unsprung mass of the vehicleby a link 2l as shown in Figs. l to 3 inclusive. Link 2i is preferablyprovided with any suitable means for adjusting its length so that it mayserve as an easily accessible means for altering the normal ridingheight of the vehicle as will be described later.

An oscillatable lever or walking beam Ht is supported upon the shaft l5within the chamber |00 of the housing portion 36. Lever H6 is T-shaped.The cross-head portion lll being tubular, the other standard portionbeing a cam extension |18 which projects through an opening |02 in thewall 10| into the cylinder |03. Shaft i5 extends through a transverseopening midway between the ends of the tubular cross-head portion of thelever H0, the axis of said shaft H5 intersecting the longitudinal centerof the tubular cross-head portion That portion of shaft H5 extendingthrough lever IIB and particularly that portion of said shaft exposedinside the tubular cross-head por tion has two diametrically oppositesubstantially iiat cam surfaces ||9 parallel to each other and equallyspaced from the axis of the shaft. For purposes to be described thesurfaces ||9 are slightly arcuate, the corners where they meet thecylindrical surfaces of shaft H5 being rounded and all equidistant fromthe axis of the shaft.

To secure the lever H0 to the shaft, so that under certain conditionsthe lever ||t` will oscillate with the shaft and under other conditionsthe shaft ||5 may oscillate relatively to the lever, there is provided ayieldable torque connection. This torque connection comprises twoplungers |25 and |26 on each side of the shaft and slidably carried inthe tubular cross-head portion lil of on each vplunger the lever ||6. Ahead portion slidably ts the tubularlcross-head while a. reduced stemportion ,extends through an opone,

ing in an end plate In secured in lthe.respective ends. of the tubularcrossehead portion of the lever IIB. A spring :|121 surrounding thestemportion of each plunger isinterposed between Athe head portions |25and-|26 respectively andthe corresponding Vend plates I2Ii, each springurgingxits plunger into yieldahle engagement with a respeo tive ilatcamsurface of the shaft at. apre'deter mined force.

Since the two cam surfaces I i9 on the shaft are substantially nat andparallel to each other and the engaging surfaces of therespective-plunger heads |25 and |26 are at and parallel ytozeachothen'said spring loaded plunger-s normally will hold the lever ||6in aVdefinite angular-relation relatively to the shaftk I I5 and normallywill cause the shaft and lever to oscillate together. .Said springloaded plungers yieldably opposeirelative rotation between the shaft andleverand if such relative rotation does occur, the plungers .will exerta substantially constant force tendingto returnthe lever to its normalangular vposition relatively to the shaft. As the shaft is rotated andno external force is applied to thelever H6 to oppose its rotation withthe shaft H5, aswill later be described, said lever I I6 or moreparticularly its cross-head portion II'I willengage one or the othervalve actuating plungers 6l or 86, depending upon the direction ofrotation of lever IIB by the shaft II5, moving the plunger to actuateeither the linflation control valve pin 6'I or the deflation controlValve-pin 86 respectively. Continued rotation of the lever `H6 Aby shaftI I5 in the one or the other direction as mentioned will eventuallybring the one or the other end of the cross-head portion I|1 of lever||`8 into positive engagement with the immovable housing portion 35, thebottom surface of which forms the ceiling for'the chamber |00 containingthe lever II6, so that from thereon, the shaft must rotate relatively tothe lever H6. vUnder these conditions rdiametrically opposite roundedcorners of the flattened portions I Il)v of shaft l I5 will commence toride over the engaged surfaces of the plunger heads |25 and |26,seefFig. 5, forming two moment arms of equal length, acting to move saidplungers against the equal opposing force of their springs |21. Thisprovides ade nite torque which maintains the lever in this operatedposition While the shaft is rotating relatively to said lever and'at thesame time provides a means which will quickly return thellever IIB toits normal angular position relatively to the shaft when the rotation ofthe shaft is again reversed. `From thedrawings Figs. 4 and 5 it mayreadily he seen that 'this torque connection is eiective as describedabove when thes'ha'ft rotates in either direction.

The two substantially flat parallelicam surfaces H9 of shaft ||5 Lareslightly arcuated `to reduce operating noises to a minimum. Thearcuated' cam surfaces Il!) effect a gradual' increase in length of themoment arms actuating thegplungers against the effect of theirrespective springs |21.

Thus the. control device ofthe present im'eration,l is provided with, a.yieldable torque connection zbetween its drive shaft and theval've.actuating lever, said connection exerting a substantially constant,predetermined torque'to move theA said lever with the shaft apredetermined distance in either direction and maintaining said `leverinthe operated position Whilethe shaft continues' its lrotation in thisone direction-enflamme'the reverse movement lof the shaft untii saidshaft and leverassumetheirnormal angular relationes 16., the fmorerapid' 'and' o! lessi-amplitude move raise the vehicle frame .too high-asftravelspans are limited and overtravel eliminated.

.Thepresent control device is designed to eifect inflation .orde'ationfof the air springs of the vehicietowhich it is applied, onlyunder certain conditions. Whenthe deviceis installed on a vehicle, thehousingZ is attached to the sprung mass or vehicleirame while theoperating arm 2| ofthe devicefls attached to the unsprung mass orvehicle yaxle by a. linkfZl. Any approaching or separating movementsofthe sprung and un' Sprungxmasses ofthe vehicle will `therefore causerelative movements between .the housing and the operating armvzl withitsshaftL I I5 journalled in said'housing. Due to4 such relativemovements, the shaft Itwill be oscillated in its bearing in thehousing.

Such `approaching or.. separating movements of the :sprung land unsprungmasses of the vehicle, may be caused vin ltwo ways. One way is byvarying the normal load on the sprung mass. `Increasingthe`load-on thesprung mass will cause it to-.moveftoward the unsprung mass thereby`compressing they air springs. `If this increased' load is excessivathedanger of bottoming," that sstriking of `the frame on the axle of thevehicle ispresente'd. The ordinary practice of overcoming this is toprovide stiffer springs which tends to a. harder,:stiiler ride, or toraise the normalloadriding level of the vehicle frame, which when novload is on the frame tends to for safe opera-l tion Vespeciallyathigher speeds. The relative movement or the sprung (vehicle frame) andunsprung (vehicle'axle) 'masses due to variable loading isfconsiderablyslower than such movement caused by the vehicle striking: ruts or bumpsin the roadway over which it is being operated. Theselatter movements.are very rapidat times and ofsmallfampiitude.'

It is essential, and the control device of the present invention isdesigned and constructed, to effect. inflation donation of the airsprings in response only to predeterminately slowrelativemovementsbetween the frame and axle of the vehicle caused byloading or unloading of' the vehicle .and-.to vbe completely inffectiveto cause adjustmentsrofftheair springs in response to :the more rapidmovements of said frame and-axle causedby operating the vehicle over anirregularidad surface.

'order that the inflation-vaive'dis actuated permit ixiiiation of theair springs, only in response to nredeterminately slow. movement of theSp :nass trav-ard` the unsprung massV due to increasing loaden, saidspmng mass .and the dei-lation control valve e5 is actuated to deflatethe. air springs only `in response Ato predeterminately :slew:separating -movements `of fandfunepruuepmasses due to decreasing' the.lasciv thefeprungmass; 'mdfin order that ments of said masses :due to'road conditionswill nctbe eective to cause the 'said'valves lto beactuated, the device is provided with a movement dampener or impedingmechanism which, combined with the yieldable connection between theshaft and lever 116, forms in effect a time delay device which permitsthe control device to be effective at slow movements of the sprung andunsprung masses and ineffective -at the faster movements thereof.

This movement dampener or impeding mechanism comprises a two piecepiston` 105 reciprocative in the cylinder 103 ofhousing portion 36.Piston 105 consists of two cylindrical blocks. 130 and 131 tied togetherby two bolts 132 and 133. Bolt 132 slidably extends through block 13m4and is threaded to block 131 while bolt 133 slidably extends throughblock 131 and is threaded to block 130. A spring 134 isl interposedbetween the head of bolt 132` and block 13.1114 and a similar spring isinterposed between-fthe head of. bolt 133 and the block 131. Thesesprings urge the blocks toward each other lso that the wear pieces 131secured in recesses intheadjacent surfaces of blocks 130 and 13'1 are4urged into 4constant .1

engagement with the cam portion 118 of the lever 1 16. Each piston blockhas a ythrough passage connecting the respective fluid displacementchamber, formed in the cylinder by Said 10100K,

with the iiuid reservoir space between Athe two l blocks. The passage inblock 130 is designated bythe numeral 136 and ,the'one in block 131 bythe numeral 135. Each passage has a one way check valve whichpermitsfluid to flow from the central reservoir space between -the pistons intothe respective uid displacement chambers 103 or 101, but not from saidchambers into the reservoir. Thus any shortage of fluid in either one ofsaid chambers 106 and 101 due to fluid leakage, will be compensated forby said check valves. 1

From the aforegoing description it may be seen that the lever 116 ismechanically connected to the reciprocative piston 105 of the movementdampener and thus any tilting movement of said lever or walking beam ineithervdirection, is transmitted to the piston 105 causing it todisplace fluid from one displacement chamber through the restrictedpassage 08 into the op-. posite displacement chamber.

As has been mentioned previously, the yieldable torque device connectingthe lever 111i to shaft 115 and the dampening device including nuiddisplacement piston 105, form in eiect a time deiay device which causesthe control mechanism to function in the desired manner. -Since theyieldabletorque drive exerts a' relatively constant torque to move thewalking beam 1 i6 with the shaft 115,. it also exerts a relativelyconstant force at the end of the cam extension 11S toY move the piston105 in cylinder 103. This movement of the piston 105 causes iiuid to bedisplaced from oney displacement chamber through the predeterminatelyrestricted :passage Hi8K into the opposite displacement chamber. Sincethe actuating force is relatively constant, a denite maximum period oftime is required for a piston movement sufficient to effect operationofv the control valves through a corresponding angular movement of cam 118 and walking beam or lever 110. Accordingly, slow relative movementsbetween the sprung and unsprung masses due to variation in load on .thesprung. mass cause 'ai force in one" direction to beVA appliedfto'piston' #05' for a suicient" length of time to -eectcontrol range orwhat might ation of the air springs.

lvalve operation. Onthe other hand', insufficient time Vis allowed forvalve operation when the n nation ordeation has been completed thesehigh rate movements -will also have no effect on the position of thewalking beam or lever 110 and the control valve operation since theforce on the dampener piston 105, due to the yieldable torque drive,will favor the relative movement due to load change and persist over alonger period in that direction than in the other until imiation ordeation of the air springs has been completed. y

^ The control device of the present invention is designed to becomeeffective to cause inflation or deation of the air springs when thespring mass is lowered or raised below or above the selected normalriding height. More specifically, it is not desirable that inflation ordeiiation be effected immediately upon an increase or decrease of load.On the contrary, the present device is designed and constructed topermit the valve actuating lever 116 to move lthrough an idle be termeda dwell during which it is not eiective to actuate the valves. Thispermits a predetermined increase or decrease inload on the sprung massbefore the device becomes effective to start 'mation or de- With respectto the outer end of operating arm 21, this idle range of movement ordwell is the distance or angle through which the arm may be moved afterone of the control valves is closed and the other control valve startsto open.

After the device is attached to the vehicle, the link 21, preferablyequipped with a length adjusting means, may be adjusted to provide forthe desired normal load riding height. Ii this height is to be raised,the link is lengthened and if it be desired to lower the normal loadriding height, the link must be shortened.

* Operation of the device At a selected normal load, the `sprung mass ior frame of the vehicle is at a predetermined .L movement is slow, thelever 11E will move with the shaft and likewise piston 105 of thedampener will move to the right as regards Fig. 4. As aforedescribed,lever 116 may be moved through a certain range of movement from its deadcenter position as shown in Fig. 4 before its inflation valve steml isengaged by the actuating plunger 6'1 and moved thereby to openvcommunication between the source of fluid pressure andthe' airsprings. fThus a 'predeterminedincrease in the normalfload of the bus is necessarybefore the 'air Spring inflation operation is started. When the rightend of lever H6 strikes the bottom surface of housing portion 35.counter-clockwise rotation of lever I6 by shaft H5 is arrested. however,if the lever 2 I and its shaft H5 continues to rotate counterclockwise.as regards Fig, 5, due to load application, the yieldable torqueconnection will yield to permit relative ,rotation between shaft H andlever H5, but sai-d connection will still exert sunicient torque to holdthe lever in the inflation valve actuating position.

As the air springs are being inflated, their ex;- pansion, due to suchinflation, willgcause the sprung mass to be lifted toward themean'riding. height. This results in a consequent clockwise rotation ofthearm l2l and shaft H5 which, due to the torque connection immediatelyrrotates the lever H5 clockwise to return it to the dead center positionin which the inflation control valve is again fully closed. Thereforethe sprung mass with its added load is again maintained at its normal ormean riding height, If additional passengers board the bus, theadditional load will again cause the aforedescribed inflation operationto be repeated.

If however, the load is reduced by the discharge of passengers, then theair springs will expand and lift the sprung mass away from the unsprungmass. As this occurs, the arm 2l and its shaft Will be rotatedclockwise-as regards.

Figs, 3 and 4. Now lever H6 will be moved into the position as shown inFig. 5, in which the deflation control valve mechanism is fully openedto permit communication vof the air springs with the exhaust port toatmosphere. This permits air pressure from said air springs to escapeand results in a deflation of the air springs and a consequent loweringof the sprung mass. As the sprung mass moves toward the unsprung massdue to such deflation of the air springs, the shaft H5 and its arm 2|will again be rotated counterclockwise. This will cause theA return; oflever HS to its normal dead centerv position in which both inflation anddeflation control valves are inoperated and closed. Again the sprungmass is in its normaler mean riding; height position.

As long as the load on the sprung mass is maintained, substantially noinflation or doa-- tion of the air springs will obtain. However,` if

this load is increased or decreased, or,` ifv the masses are movedrelatively at a rate and amplitude corresponding to those caused-by loadvari ations, then the device of thepresent invention becomes operativeto effect inflation or deflation of the air springs respectively toreturn the sprung mass to the mean riding level under the changedconditions and retain it there as long as said conditions exist.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, allcoming within the scope of the claims which follow.

What is claimed is as follows:

1. A mechanism for controlling the action of two normally inactivecontrol devices, said mechanism consisting of an oscillatable levertiltable in one direction to engage and render the said one controldevice active and in the other direction to render said other deviceoperative; an oscillatable shaft carrying said lever so as to betiltable thereon; a predeterminately yieldable torque connection betweensaid shaft and lever normally effecting movement of the lever with oftwo control devices, said actuator consisting` of an oscillatable shaft;a lever on said shaft and rotatable relatively thereto, said lever beingoperative to engage and actuate one or the other of said control devicesdependent upon the direction of lever rotation; a yieldable torqueconnection between said shaft and lever, ynormally effecting rotation ofthe lever with the shaft; and a movement dampener connected to andoperated by said lever, said dampener impeding the movements of saidlever to effect yielding of said torque connection and thereby relativerotation of the shaft to the lever at predetermined oscillating speedsof the shaft.

3. An actuator for operating one or the other of two control devices,said actuator consisting of an oscillatable shaft; a lever supported bysaid shaft so as to be rotatable relatively thereto, said lever beingoperative to engage and actuate either control device; a movementcontrolling dampener operatively engaged by said lever; and a resilientconnection between the lever and shaft, operatively securing the leverto the shaft for effecting their unified rotation during normaloscillations of said shaft, but, under the influence of the dampener,yielding and permitting the shaft to oscillate relatively to the leverwhen said shaft oscillations are at a predetermined rate and amplitude.

4. An actuator for operating one or the other devices; means supportedby the lever and en gaging the shaft, said means yieldably securing thelever to the shaft so that normally one rotates with the other and amovement impeding device operatively connected to the lever and beingoperative to render said means ineectiv'e to secure the lever to theshaft when the oscillations of said shaft attain a rate exceeding apredetermined normal.

5. An actuator for operating one or the other of two control devices,said actuator consisting of a housing supporting an oscillatable shaft;-a three armedlever in said housing, supported by the shaft so as to berotatable relatively thereto, two arms of said lever being adapted toengage and actuate said control devices respectively when the lever ismoved by the shaft; a yieldable torque connection normally completelysecuring the said lever to the shaft for transmitting oscillatorymovements of the shaft to the lever; and a movement dampener in thehousing, engaged by the third arm of the lever and movable thereby, saiddampener being operative to resist oscillations of the lever by theshaft when said oscillations exceed a predetermined rate, whereby theeffect of the torque connection completely to secure the lever to theshaft is overcome.

6. An actuator for operating one lor the other of two control devices,said actuator consisting of a housing supporting an oscillatable shaft;a three armed lever in said housing, supported by the shaft so as to berotatable relatively thereto, two arms of said lever being adapted toengage and actuate said control devices respectively when the lever ismoved by the shaft; a yieldable torque connection carried by the leverand er1- 1,1., gaging the' shaft for yieldably securing the lever to theshaft normally to effect their concurrent rotation; and an hydraulicdashpot in the housing, said dashpot having a fluid displacement elementengaged and moved by the third arm of said lever, said dashpot impedingthe movements of the lever to effect yielding of the torque connectionand rotation of the shaft relatively to the lever at predeterminedoscillating speeds of the shaft.

- 7. An actuator operative in opposite directions for moving controldevices, said actuator consisting of a housing; a shaft supported in thehousing so as to be oscillatable; a T-shaped lever, the cross armportion of which is tubular, said portion intermediate its two ends,having a transverse opening through which an oppositely disposedflattened portion of the shaft extends, roy tatably to support saidlever on the shaft; av

spring loaded element in the hollow portion of tne lever, on each sideof the shaft, each element being urged upon an adjacent flat surfaceprovided on the shaft for yieldably securing the lever to said shaft sothat normally the lever is oscillated with the shaft; and a motiondampening device in the housing, engaged and actuated by the uprightportion of the lever, said device consisting of a closed end cylinderprovided by the housing and containing a fluid displacement pistonconnected with the lever and forming oppositely disposed iiuiddisplacement chambers, the housing having a valved duct connecting bothsaid displacement chambers to provide a fluid restricting connectiontherebetween, said dampening device impeding the movements of the leverto elfect relative movement of the shaft and lever when the oscillationsof said lever exceed a predetermined rate and amplitude.

8. A mechanism for actuating two normally inactive control devices, saidmechanism comprising in combination, a housing; an oscillatable shaftsupported by said housing; an actuating arm secured to the shaftexteriorly of the housing; a second lever, within the housing, carriedby the shaft so as to be rotatable relatively thereto, said second leverbeing movable to engage one or the other of said control devices toactivate them; means on the second lever and engaging the shaftyieldably to secure the second lever to the shaft to effect oscillationof the lever with the shaft; and a movement impeding device in thehousing, operatively connected to the second lever for impeding itsmovements and causing said means to yield and release the shaft topermit it to oscillate at speeds in excess of those at which said meansis effective to maintain operating connections between the' shaft andsecond lever.

9. In an air spring system for supporting a sprung mass relative to anunsprung mass and having separate valves for controlling supply of airto the system and exhaust of air from the system to maintain the springsystem in a substantially uniform operating position irrespective of theloading condition upon the system, the improvement in the actuatingcontrol for separately operating the valves controlling supply andexhaust of air in the system, comprising, an oscillatable shaft forconnection with a movable mass of the air spring system for oscillationthereof upon relative movement between the sprung mass and the unsprungmass with which the control is to be connected, an operating membercarried on said shaft and oscillatable thereon in the same directions ofoscillation as said shaft for controlling separately actuation of thevalves of the air spring system by the oscillations of the member, ayieldable torque connection between said shaft and said member normallyto maintain identical oscillation of said member with fsaid shaft, and amovement dampening device operably engaged by said member to resistnormally identical oscillation of said member with said shaft abovepredetermined oscillating speeds and amplitudes of oscillation to avoidactuation V'of the valves of the air spring system above suchpredetermined oscillating speeds and amplitudes, said torque connectionyielding to permit of such oscillations of said shaft relative to saidmember`A and to also maintain connection between said member and saidshaft for identical oscillation of said member with said shaft belowsaid predetermined oscillating speeds and amplitudes for actuation ofthe valves of the spring system in response thereto.

EDWIN F. ROSSMAN.

References Cited in the f'lle of this patent UNITED STATES PATENTS

